1. Field of the Invention
Embodiments of the present invention generally relate to semiconductor manufacturing, and more particularly to a vacuum chuck assembly for use in a processing chamber.
2. Description of Related Art
In the manufacture of integrated circuits (ICs), substrates may be heated to high temperatures so that various chemical and/or physical reactions can take place. Thermal processes are usually used to heat the substrates. A typical thermal process, such as annealing, requires providing a relatively large amount of thermal energy to the substrate in a short amount of time, and thereafter rapidly cooling the wafer to terminate the thermal process. Examples of thermal processes currently in use include Rapid Thermal Processing (RTP), impulse (spike) annealing, scanning laser anneal techniques, and pulsed laser techniques. Heated vacuum chucks are generally used to secure substrates in process chambers during these thermal processes.
The planarity of the substrate surface is quite important throughout the manufacture of integrated circuits; especially during a pulsed laser anneal process such as a dynamic surface anneal (DSA) process. During a DSA process, a substrate is scanned with a line of radiation emitted by a laser in order to facilitate the annealing process. The depth of focus of the anneal laser is greatly influenced by several factors including the planarity of the wafer surface. Thus, the support surface of the vacuum chuck which holds the wafer has to be as planar as possible. It generally takes a lot of effort to planarize the whole support surface of the vacuum chuck for ensuring the planarity of the wafer surface. Additionally, the heated vacuum chuck is very likely to bow upwards as the center of the chuck heats up and the periphery of the chuck loses heat. The warped chuck may cause warpage of the wafer held thereon, thus greatly reducing the planarity of the wafer surface. Also, the electrical connectors coupled with the heated vacuum chuck may be damaged or melted by overheating in the process chamber.
Therefore, it is desirable to have a vacuum chuck assembly and a process chamber equipped with the vacuum chuck assembly for improving the aforementioned disadvantages of the vacuum chuck.